Astrophotography diagnosis of NGC 7380: Noise / underexposure and tracking drift

Very favourable conditions. A Bortle 2 sky is as good as it gets for narrowband, and the measured background confirms it: no instrumental or light pollution gradient was detected, the only measured variation corresponds to the extended structure itself. The Moon is reported 27.3 degrees above the horizon but 73 degrees from the target, with contradictory illumination values between the moon field (92 percent) and the context string (9 percent): either way, at 73 degrees separation and through a narrow OIII filter its impact stays negligible and no lunar gradient is visible. In short, nothing in the sky limits this image: the limiting factor is integration time, not conditions.

A coherent but under-exploited setup. At 835mm and 0.464 arcsec/px you are clearly oversampled: the measured 8.7px FWHM corresponds to roughly 4 arcsec, which is seeing or tracking, not useful resolution. Software binning 2 would give you 0.93 arcsec/px, cleaner stars and a welcome signal gain in OIII. The 1.48 degree field frames NGC 7380 comfortably with room to spare, so framing is not an issue. On settings, 180s in OIII under Bortle 2 is too short: the background stays glued to the black point (e_margin 1.39). Move to 300 to 600s, the sky allows it with no risk of background saturation.